Communifire - Enterprise Social Collaboration Software
Tettra - Tettra is a company wiki that helps teams manage and share organizational knowledge.
DigitalChalk - Online Training Software and Learning Management System (LMS)
Perfect Wiki - Build and organize your knowledge base of company resources without switching between workspaces
Workplace by Facebook - Connect everyone in your company and turn ideas into action.
Pages by Process Street - Pages is a free-for-everyone knowledge base from Process Street.Try it out!